In order to improve durability and fraying resistance of toothed belts, it has been commonly practiced to bury fibers known as tooth sheet into a surface of their tooth parts. By using a tooth sheet, the durability of tooth parts and the fraying resistance of the rubber surface are improved. Fibers woven in a form of a sheet are generally employed as such a tooth sheet. A surface of the tooth sheet is generally processed by various treatment agents for enhancing adhesion of the belt body with its rubber matrix. As an example, a tooth sheet impregnated with rubber cement including a filler, such as carbon, after processing with a liquid mixture of a condensate of resorcinol and formaldehyde and latex is disclosed in JP7 (1995)-217705A. As another example, a tooth sheet processed with a rubber composition obtained by mixing N, N′-m-phenylene dimaleimide into hydrogenated nitrile rubber is disclosed in JP7 (1995)-259928A.
While adhesion under a static test of the conventional tooth sheets processed with the treatment agents is relatively high, the conventional tooth sheets easily crack between themselves and cords or rubber matrixes due to their poor integration with the belt parts when run for many hours as a belt. As a result, troubles were prone to arise, such as chipping in the tooth part. In addition, it was necessary to protect the environment during the manufacturing processes when a tooth sheets is treated with a conventional treatment agent using an organic solvent.